Connection management system, and a method for linking connection management server in thin client system

ABSTRACT

An exemplary object of the present invention is to suppress the load on each server and network traffic. To achieve this, a plurality of connection management servers are installed so that any of the connection management servers executes acceptance of a connection request from a thin client terminal. Further, the connection management servers manage the states of clients in order to hold the states of the respective clients, and each of the connection management servers searches a client that can be connected by the thin client terminal according to a connection request from this thin client terminal, and replies with the search result to the thin client terminal, and a range of the connection management servers for executing the search of the client is limited for each connection request from the thin client terminal to the thin client server.

CROSS-REFERENCES

This application is based upon and claims the benefit priority fromJapanese patent application No. 2010-178712, filed on Aug. 9, 2010, thedisclosure of which is incorporated herein in its entirety by reference.

BACKGROUND

The present invention relates to a connection management system and amethod for linking a connection management server in a thin clientsystem.

In a conventional client-server formed system, a PC having a magneticdisk device or the like is used as a client terminal, but recently thereare cases in which one user uses a plurality of PCs or one PC is sharedfor a plurality of businesses, because business is becoming morecomplicated, and as a result, the management cost of a client terminalis increasing, which is partially due to the need for more complicatedsoftware for a client terminal. Furthermore, the existence of such astorage device as a magnetic disk device in a client terminal increasesthe risk of information leakage.

This means that today, in some cases, a business system is constructedby a combination of a diskless terminal (such a storage device as amagnetic disk device is not equipped) or a terminal in which writing toa disk is disabled (hereafter called “thin client terminal”) and aserver (hereafter called “thin client server”) where data is held, andwhere an operating system (OS) and business applications are executed.

A thin client server which executes business applications, that wereonce executed by a client terminal in a conventional client-serverformed system, has a virtually constructed client as an execution unit(execution image) for each thin client terminal, and in the client, anOS, business applications and data, which are assigned by the thinclient terminal for each connection, are installed. Generally a thinclient server manages a plurality of thin client terminals, therefore aplurality of clients operate on a same thin client server.

In such a thin client system, a user at a thin client terminal connectsto the client operating in a data center, for example, via a network,and executes applications on the client. Inputs required for executingthe applications are executed via the thin client terminal, and theresult of executing the applications is checked on the screen of thethin client terminal.

In a thin client system, a plurality of users may share a plurality ofclients, and in order to improve system convenience, a structure isrequired when a user starts using the thin client system, a client thatno other users are using is searched and assigned to the user, andconnection is made from the thin client terminal to the assigned client.For user convenience, it is also important to minimize the operationsrequired for connection. For this, a thin client connection managementmethod is proposed, where a connection management server (or aconnection management system having this connection management server)is installed, for example, and this connection management server managesthe states of all the clients, searches and available clients accordingto the request from the thin client terminal, and replies with thesearch result (e.g. see Patent Publication JP-A-2008-140306).

In the above-mentioned prior art, however, the scale of the systemincreases, and if a number of clients managed by the connectionmanagement server, and a number of connected thin client terminalsincrease, load on the connection management server becomes high andservice may drop, such as a time lag in responding to a request from athin client terminal.

SUMMARY

With the foregoing in view, it is an object of the present invention toprovide a connection management system which can minimize the load oneach server and network traffic, and a method for linking the connectionmanagement servers in a thin client system.

To solve this problem, the present inventor performed variousexaminations. A possible method for solving the above-mentioned problemis providing a plurality of connection management servers to distributeload. There are some possible ways of implementing load distribution bya plurality of servers, as mentioned below, but each way has a problem.Examples will now be described.

The first method is that each connection management server completelyindependent from one another, managing clients and requests/responses tothin client terminals. This is time consuming for the user, since theuser must specify which connection management server a connectionrequest is sent to, depending on which client the user wants to connectto.

The second method is that necessary information is managed by one database, and all the connection management servers access the data base tomanage the state of the clients, and perform the processing of therequests/responses from the thin client terminals. A problem with thismethod is that all kinds of processings related to the data base areperformed by a server where this data base is running, and this servercould become a bottleneck of the thin client system.

The third method is that each connection management server has a database, and each server independently manages the states of clients, andperforms processing of requests/responses from the thin clientterminals, synchronizing the information of the respective data baserequired for processing. The available methods for synchronizing thedata bases are a method for synchronizing periodically, and a method forsynchronizing every time information in a data base changes. In order toprocess the connection management maintaining consistency, the state ofthe clients are constantly monitored, so in the case of the formermethod, a same client may be assigned to a plurality of users at thesame time since each server can not access the latest information, whilein the case of the latter method, communication and processing forsynchronization are performed frequently and the load on each server andnetwork increases, therefore this method is not appropriate for aconnection management system.

The fourth method is that each connection management server has a database, and only information related to the clients that each servermanages is stored in the data base of each server, and when each serverprocesses a connection request from a thin client terminal, the serversare linked and the client is assigned by exchanging information amongits servers. A problem of this method is that information is exchangedwith all the connection management servers every time a connection isrequested from a thin client terminal, and load on each server andnetwork increases.

The present inventor performed various examinations focusing on theabove-mentioned methods for implementing load distribution andrespective problems, and reached new knowledge that could solve theproblem. The present invention, which is based on this knowledge, is aconnection management system comprising a plurality of connectionmanagement servers each managing connection from a thin client terminalto a thin client server, wherein the connection management serversmanage states of clients in order to hold the states of the clients, andeach of the connection management servers executes a search of a clientavailable for the thin client terminal according to a connection requestfrom this thin client terminal, and replies with the search result tothe thin client terminal, and a range of the connection managementservers for executing the search of the client is limited for eachconnection request from the thin client terminal to the thin clientserver.

In this case, it is preferable that each of the connection managementservers comprises a server configuration information table which stores,for each of the connection management servers, identificationinformation of a group to which the connection management serverbelongs; a request window unit which accepts a connection request fromthe thin client terminal, selects a connection management server whichexecutes the search of the client based on a group specified by a user,and transmits a search request to the selected connection managementserver; and a connection destination management unit which receives thesearch request, and selects a connectable client out of target clientsthat can be assigned to the thin client terminal to respond to therequest.

In the connection management system, it is preferable that the clientsare grouped.

A thin client system according to the present invention comprises: aplurality of thin client terminals; a plurality of thin client servershaving clients which are connected from the thin client terminals toexecute applications; and the above-mentioned connection managementsystem.

The present invention is also a method for linking a connectionmanagement server in a thin client system having a plurality of thinclient terminals, a thin client server having a client which isconnected from the thin client terminals to execute applications, andthe connection management server which manages connection from the thinclient terminals to the thin client server, comprising the steps of:installing the connection management server in plurality so that any ofthe connection management servers executes acceptance of a connectionrequest from the thin client terminal; the connection management serversmanaging states of clients in order to hold the states of the respectiveclients, and each of the connection management servers searching aclient that can be connected by the thin client terminal according to aconnection request from this thin client terminal, and replying with thesearch result to the thin client terminal; and limiting a range of theconnection management servers for executing the search of the client foreach connection request from the thin client terminal to the thin clientserver.

In the method for linking the connection management server according tothe present invention, load on each connection management server (e.g.CPU load) and network traffic can be minimized by appropriately limitingthe range of the connection management servers for searching availableclients.

It is preferable that each of the connection management serversundertakes acceptance of the connection request from the thin clientterminal, and response of the result of selecting a connectable client,and refers to a configuration information table which stores informationon each of the connection management servers, when a range ofdestinations of transferring the connection request from this thinclient terminal is determined.

It is preferable that each of the connection management serverscomprises a connection destination management unit which searches aconnectable client group, selects a client that can be connected by thethin client terminal, and manages a state of the client, the methodfurther comprising a step of transferring the search request to theconnection destination management unit in this connection managementserver and to the connection destination management unit in otherconnection management servers, determining a range of transferdestinations, and tabulating the responses to the transferred searchrequests.

In the present invention, the request window unit in the connectionmanagement server undertakes acceptance of a connection request from athin client terminal, and undertakes a request/response (includingselection of a client to which the thin client terminal can beconnected, and reply of this result), which were conventionallyperformed by the connection destination management unit. By introducingthis request window unit, the internal functions of the connectionmanagement server can be separated into a hierarchy for communicatingwith the outside (request window unit), and a hierarchy for searching anavailable client group (connection destination management unit), and aconfiguration more suitable for linking the connection managementservers can be established without changing the conventional connectiondestination management unit at all.

The server configuration information table is a table which is referredto when a range of the transfer destinations of the request isdetermined. The more transfer destinations exist, available clients canbe searched in a wider range, but a heavier load is applied on thenetwork and servers. Therefore transfer destinations are limitedutilizing the characteristics of the thin client system in which aplurality of users share a client, so as to decrease load.

In many cases, a user belonging to a specific group (department) usesone client which the connection management server assigned, out of someclients belonging to a specific group (assigned to a department by anadministrator) using only some specific thin client terminals (personalstationary terminal of user, mobile terminal, terminal shared in adepartment). In this case, clients which are frequently connected arespecified for each thin client terminal, so a connection managementserver managing the clients which are frequently connected for each thinclient terminal is registered in advance as a connection managementserver to which the thin client terminal is connected first, so that anavailable client can be searched within the local server (thisconnection management server) without searching other connectionmanagement servers. Therefore in this thin client system, applying loadon other servers and the network can be prevented.

If a client group is managed by a part of the connection managementservers of the thin client system, clients can be searched only in thispart of the connection management servers. Then applying load on otherservers can be prevented.

In some cases, from a shared thin client terminal installed in a placethat is different form a normal location of use, such as on a businesstrip, the user may connect to a client group the user normally uses (adifferent client group from one which the terminal in the business triplocation is often connected to). In this case, an available client cannot be found merely by searching a specific connection managementservers registered in the shared thin client terminal. Therefore in sucha case, it is preferable that the user can request searching from theconnection management servers in a wider range, or all the connectionmanagement servers.

According to the present invention, load on each server and networktraffic can be minimized by appropriately limiting the range of serversto be searched.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram depicting a thin client system according to anexemplary embodiment of the present invention;

FIG. 2 is an example of a group information management table;

FIG. 3 is an example of a connection destination setting informationtable;

FIG. 4 is an example of a client state management table;

FIG. 5 is an example of a server configuration information table; and

FIG. 6 is a sequence diagram depicting an example of a procedure ofconnection management when connection is performed from a thin clientterminal to a thin client server.

EXEMPLARY EMBODIMENT

A configuration of the present invention will now be described in detailaccording to an exemplary embodiment shown in the drawings.

FIG. 1 is a configuration example of a thin client system according toan exemplary embodiment of the present invention. The illustrated thinclient system is comprised of a plurality of thin client servers 1, aplurality of thin client terminals 3, and a plurality of connectionmanagement server 2 which manage connection from each thin clientterminal 3 to a client 11 of each thin client server 1. The connectionmanagement servers 2 are disposed in a network connecting the thinclient servers 1 and the thin client terminals 3.

Each thin client server 1 has a client 11 which is a virtuallyconstructed computed machine. An OS (client OS), business applicationsand data are installed on each client 11, and each client 11 has a stateacquiring unit 111. Each client 11 is assigned to the user for use eachtime the user connects to the connection management server 2 from thethin client terminal 3. The state acquiring unit 111 has a function totransmit the state of the client 11 (e.g. power ON, power OFF, log OFF,log ON) to the connection destination management unit 21 of theconnection management server 2.

The connection management server 2 has a connection destinationmanagement unit 21, a request window unit 22, a group informationmanagement table 23, a connection destination setting information table24, a client state management table 25, and a server configurationinformation table 26 (see FIG. 1).

The request window unit 22 receives a connection request to the client11 from the thin client terminal 3, transfers the request to theconnection destination management units 21 in the local server and otherservers, determining the range of the transfer destinations, tabulatesresponses to the transferred requests, and returns the received responseto the request to the thin client terminal 3. This request window unit22 undertakes the acceptance of the request from the thin clientterminal 3 and the response thereto, which were conventionally performedby the connection destination management unit 21. By introducing thisrequest window unit 22, a hierarchy for communicating with the outside(this request window unit 22) and a hierarchy for searching an availableclient group (connection destination management unity 21) can beseparated, and a server linking configuration (a linking configurationfor a plurality of connection management servers 2 to support the statemanagement of many clients 11 and connection from many thin clientterminals 3) can be established without changing the conventionalconnection management unit at all.

The connection destination management unit 21 has a function to search aconnectable client group, for the request transferred from the requestwindow unit 22, and determine a connection destination client to whichthe thin client terminal 3 is connected to, and manage the states of theclients 11.

The group information management table 23, the connection destinationsetting information table 24, the client state management table 25, andthe server configuration information table 26 respectively storenecessary information for the connection destination management unit 21to manage connection.

The group information management table 23 stores, as FIG. 2 shows,information on a user name (user ID), a thin client terminal 3 and aclient 11, and information on a group where each user, thin clientterminal 3 and client 11 belong. The connection destination settinginformation table 24 stores, as FIG. 3 shows, information on a user(user ID) group and thin client terminal group which can be connected toeach client group (linking information). The client state managementtable 25, stores, as FIG. 4 shows, information for each client on thestate of the client 11. The server configuration information table 26stores, as FIG. 5 shows, information of each server used for determiningtransfer destination of a request from the thin client terminal 3. Thedata in the group information management table 23, the connectiondestination setting information table 24 and the server configurationinformation table 26 must be set before starting operation of the thinclient system (before the user connects to the client 11).

The thin client terminal 3 has a connection unit 31, a connectiondestination control unit 32 and a connection management serverinformation file 33. In the connection management server informationfile 33, information (IP address) of a connection management server 2,to which each thin client terminal 3 should be connected, is specifiedin advance. The connection management server 2 specified here is aconnection management server managing clients 11 which are frequentlyused from this terminal. The connection destination control unit 32 hasa function to obtain input from the user on the user ID information andsearch range on the thin client terminal 3 and a search range, transmitthe input information and thin client terminal information of the thinclient terminal 3 to the request window unit 22 of the connectionmanagement server 2 specified by the connection management serverinformation file 33, then obtain information on connectable clients fromthe request window unit 22, and transmit this information to theconnection unit 31. The connection unit 31 has a function to connect tothe client 11 based on the received information.

Now a connection management procedure when connection is performed froma thin client terminal 3 to a thin client server 1 will be describedwith reference to FIG. 6.

When the user attempts to connect to a client 11 using a thin clientterminal 3, the user inputs the user ID to the thin client terminal 3,and specifies the search range at the start of using the thin clientterminal 3. Then the connection destination control unit 32 obtains theuser information (user ID) which the user input and the specified searchrange, then transmits the user information which was input, informationof the thin client terminal 3 which the user is using (thin clientterminal information), and the search range to the request window unit22 of the connection management server 2 specified by the connectionmanagement server information file 33 (hereafter “default connectionmeasurement server”), and request a list of an available client group(step Z1). The request window unit 22 of the default connectionmanagement server 2 receives the user information, the thin clientterminal information and the search range, and determines a connectionmanagement server 2 to be the transfer destination of the connectionrequest based on the specified search range and the server configurationinformation table 26 (step Z2). At this time, the connection managementserver 2 determined as the transfer destination may include the defaultconnection management server.

A method for determining a transfer destination server will now bedescribed with reference to FIG. 5. For example, it is assumed that instep Z1, a connection management server #1, which is the defaultconnection management server, received information on “servers of whichvalue of the range identifier (group ID) is 1 or less” as a search rangefrom the thin client terminal 3. In this case, in step Z2, the defaultconnection management server #1 refers to the server configurationinformation table 26 in the local server, and extracts the servers of“which value of the range identifier is 1 or less”. Thereby theconnection management server #1 and the connection management server #2are determined as the transfer destination servers. The connectionmanagement server #3, of which the value of the range identifier is 2,on the other hand, does not become a transfer destination. In step Z2,the connection management servers 2 to be the transfer destinations canbe freely changed depending on the way of assignment of the rangeidentifiers and the conditions to determine the search range. However ifthe user specifies a complicated search range, operability drops, so itis preferable to provide the user with simple and clear choices, such as“connect to clients in the Personnel Department”, or “search allconnectable clients”, as a user interface for the user to specify thesearch range, so that the user can easily specify the search range.

Then the request window unit 22 transfers the user information and thethin client terminal information to the connection destinationmanagement unit 21 of the connection management server of each transferdestination determined in step Z2 (including the default connectionmanagement server in the case of this exemplary embodiment) (step Z3).The connection destination management unit 21 of each connectionmanagement server 2 which received the user information and the thinclient terminal information extract client groups linked with thisinformation from the connection destination setting information table 24using the received user information and the thin client terminalinformation (step Z4).

Any linking method may be used, such as forming a group of clients, thinclient terminals and users, and linking each group. Thereby an operationformat where a plurality of users belonging to a specific group, such asthe “Personnel Department”, share clients and thin client terminals, forexample, can be implemented, and the present invention is also assumingthis way of linking.

The extracted list of connectable client groups is transmitted from theconnection destination management unit 21 of each connection managementserver 2 to the request window unit 22 of the default connectionmanagement server 2 (step Z5). The request window unit 22 of the defaultconnection management server 2 tabulates lists of the client grouptransmitted from each connection management server (including thedefault connection management server in the case of this exemplaryembodiment) (step Z6). The tabulated list is transmitted to theconnection destination control unit 32 of the thin client terminal 3(step Z7). Responding to this, in the thin client terminal 3, theconnection destination control unit 32 has the user select a connectiontarget client group, out of the list of connectable client groups, andtransmits the information on the selected client group to the requestwindow unit 22 of the default connection management server 2 (step Z8).

The request window unit 22 of the default connection management server 2receives information on the selected client group, and specifies aconnection management server 2 which transmitted a list including thisselected client group (step Z9), and transfers the information on theselected client group to the connection destination management unit 21of the specified connection management server 2 (step Z10). Theconnection destination management unit 21 which received the informationsearches the client state management table 25 so as to select a client11 available for the client group, that is, a client no user is loggedon to (step Z11). Then the connection destination management unit 21transmits the information on the client 11 to the request window unit 22of the default connection management server 2 (step Z12). The requestwindow unit 22 of the default connection management server 2 whichreceived the information on the client transmits the information on theclient to the connection destination control unit 32 (step Z13).

The connection destination control unit 32 which received information onthe connection target client 11 like this inputs the information on theclient 11 to the connection unit 31 of the thin client terminal 3 (stepZ14). As a result, the connection unit 31 connects to the client 11(step Z15), and the state acquiring unit 111 on the client 11 updatesthe state of the client 11 of the client state management table 25 viathe connection destination management unit 21 (step Z16).

As described above, the connection management server 2 can search aconnectable client from a desired range for the thin client terminal 3,and has the thin client terminal 3 connect to the client 11.

As mentioned above, in the connection management server 2 according tothe present exemplary embodiment and the thin client system having thisconnection management server, a plurality of servers can perform theconnection management in the thin client system, which wasconventionally performed by one connection management server, hence alarge scale thin client system comprised of more users, thin clientterminals thin client servers and clients, can be constructed andoperated.

Furthermore, in a connection management performed by the connectionmanagement server 2 according to the present exemplary embodiment andthe thin client system having this connection management server, clients11 can be searched in a wide range only when the user connects to aclient 11 using a thin client terminal 3 which is normally not used,such as a case of a business trip, and can search minimum connectionmanagement servers 2 in a normal state. Therefore a range of the servers(connection management servers 2) for searching an available client 11in each connection request from the thin client terminal 3 to the client11 can be appropriately limited, so as to minimize the load on eachserver (e.g. CPU load) and network traffic.

While the invention has been particularly shown and described withreference to exemplary embodiments thereof, the invention is not limitedto these embodiments. It will be understood by those of ordinary skillin the art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the present invention asdefined by the claims.

The present invention is preferably applied to connection management ina thin client system comprised of a plurality of thin client terminals 3and a thin client server 1 having a client 11, which is connected fromthe thin client terminal 3 to execute applications, to performconnection from the thin client terminal 3 to the thin client server 1.

What is claimed is:
 1. A connection management system comprising a plurality of connection management servers each managing a connection from a thin client terminal to a thin client server, wherein each of the connection management servers comprises: a server configuration information table which stores, for each of the connection management servers, identification information of a group to which the connection management server belongs; a request window unit which accepts a connection request from the thin client terminal, selects a connection management server which executes the search of the client based on a group specified by a user, and transmits a search request to the selected connection management server; and a connection destination management unit which receives the search request, and selects a connectable client out of target clients that can be assigned to the thin client terminal to respond to the request, wherein the connection management servers manage states of clients in order to hold the states of the clients, and each of the connection management servers executes a search of a client available for the thin client terminal according to a connection request from this thin client terminal, and replies with the search result to the thin client terminal, and a range of the connection management servers for executing the search of the client is limited in response to the states of the clients and a load situation of the connection management servers for each connection request from the thin client terminal to the thin client server; and wherein each of the connection management servers undertakes acceptance of the connection request from the thin client terminal, and response of the result of selecting a connectable client, and refers to a configuration information table which stores information on each of the connection management servers, when a range of destinations of transferring the connection request from this thin client terminal is determined.
 2. The connection management system according to claim 1, wherein the clients are grouped.
 3. A thin client system comprising: a plurality of thin client terminals; a plurality of thin client servers having clients which are connected from the thin client terminals to execute applications; and the connection management system according to claim
 1. 4. A method for linking a connection management server in a thin client system having a plurality of thin client terminals, a thin client server having a client which is connected from the thin client terminals to execute applications, and the connection management server which manages connection from the thin client terminals to the thin client server, wherein each of the connection management servers comprises: a server configuration information table which stores, for each of the connection management servers, identification information of a group to which the connection management server belongs; a request window unit which accepts a connection request from the thin client terminal, selects a connection management server which executes the search of the client based on a group specified by a user, and transmits a search request to the selected connection management server; and a connection destination management unit which receives the search request, and selects a connectable client out of target clients that can be assigned to the thin client terminal to respond to the request; the method comprising the steps of: installing a plurality of connection management servers so that any of the connection management servers executes acceptance of a connection request from the thin client terminal; the connection management servers managing states of clients in order to hold the states of the respective clients, and each of the connection management servers searching a client that can be connected by the thin client terminal according to a connection request from this thin client terminal, and replying with the search result to the thin client terminal; and limiting a range of the connection management servers for executing the search of the client in response to the states of the clients and a load situation of the connection management servers for each connection request from the thin client terminal to the thin client server; and wherein each of the connection management servers undertakes acceptance of the connection request from the thin client terminal, and response of the result of selecting a connectable client, and refers to a configuration information table which stores information on each of the connection management servers, when a range of destinations of transferring the connection request from this thin client terminal is determined. 